The Swamp Cooler from Ruffwear helps your dog beat the heat. Just soak the Swamp Cooler in cold water, wring it out and fasten around your dog. Evaporative cooling exchanges the heat with the coolness of the stored water in the coat. The light-colored vest keeps the sun off your dog"s back for additional heat relief. Rewet the vest as needed as water evaporates to recharge the cooling action.